I realize I have been asking a lot of questions as of late, but I do yet have another one for everyone. I am interested to know more of isometric training. First off, in layman's terms, my understanding is that it is holding weight at a certain point and not performing repititons (as if squatting but just holding your squat for 30 seconds as opposed to just performing 10 reps). Correct me if this is wrong...but I am curious...do people use this more for muscular endurance, or is it more for building muscle? Lifting and moving boxes I guess would be another example...and this can be a good muscle builder...but is it the act of lifting the box up or carrying it around that is the main cause of this?

Isometric is any activity in which the muscle remains at a fixed length (which is what isometric literally means in Latin, or whatever), as opposed to isotonic, in which the tension (i.e. the weight) on the muscle remains constant.

When I was a kid, there were ads in the back of a lot of magazines, including Boy's Life, for Charles Atlas' body building course. The ads became famous for their cartoons of the skinny guy and his girlfriend sunbathing on the beach as the bully kicks sand on them, and the skinny guy can't do anything about it. Then he takes the Charles Atlas course, builds impressive-looking muscles, and the bully is afraid to kick sand on them the next time. Charles Atlas used isometrics either mostly or exclusively (I don't know, as I never took the course) for his training method.

Isometric exercise can be done against any unmoving force. You can use one body part to resist another (e.g. pressing your hands together, or trying to extend one elbow while holding the arm back with the other arm). You can press or pull on an immovable object (a wall, heavy furniture, heavy weights, etc.) Your example of holding a box is isometric; the act of lifting it in the first place, or putting it down afterwords is not, because the muscle length is changing. Any time you stop moving with the muscle under tension while doing a weight lifting exercise is isometric exercise.

Isometrics can build strength, but at a limited part of the muscle's ROM. That was the flaw of the Charles Atlas method; it didn't lead to very functional strength because the muscles weren't strong through their full ROM. Strength vs. endurance is like with isotonic exercises, but just applies to the limited part of the muscle's ROM. So relatively intense contraction for shorter time emphasizes more strength gains, contractions for longer time (which are necessarily less intense) emphasize endurance, but only for the part of the muscle's ROM near the point where the contraction is performed.

They are useful when you need to improve a portion of the ROM of a muscle's movement. I think some people use isometrics to overcome a sticking point by lifting the weight to their sticking point and then holding it there for some time.

Things like planks and bridges are isometric. I see a lot of suggestions for core exercises that are isometric. I've been using a very interesting exercise that I learned from KPj called the Pallof press, which is essentially isometric.

Sorry to go on so long. I don't actually know that much about it, or at least I didn't think I did. As a friend of mine often says, "I've already told you more than I know."

Carring heavy weight could also be thought of as isometric but it's much more than that. Farmer's walks are a good example. You carry heavy weights in your hands and then walk for distance or time. Many of your muscles are being worked isometrically, some dynamically. Many others are workings as stabilizers. Although strength and eandurance are both being worked on, the main benefit as I see it is that the body is working as 1 piece as it was intended. This type of training will fill in the gaps in your body to build a solid functional unit.

If you are interested in carries, look up articles by Dan John. His site is: danjohn.org and he posts on T-Nation.

Edit: You also mentioned Squat holds. Dr. Squat recommends overloads, or walkouts as a way of acclimatizing to heavier weights on your shoulders. The idea is that you load the bar with supramaximal weights and walk out of the rack. Ensuring you have safety pins properly in place, you then hold the bar for a few seconds and put it back. This will make your normal working weight seem lighter. You might do this as you are working up to a PR or a competition.

What should be the duration of an isometric exercise, how many sets should be done? I'm currently doing crunches in 20-30 rep range, and now I'm going to add an isometric exercise for my obliques. I'm planning to switch between crunch, side plank / side crunch, front plank every month or two. Is it ok? Or I should do only regular exercises for abs?

What should be the duration of an isometric exercise, how many sets should be done? I'm currently doing crunches in 20-30 rep range, and now I'm going to add an isometric exercise for my obliques. I'm planning to switch between crunch, side plank / side crunch, front plank every month or two. Is it ok? Or I should do only regular exercises for abs?

Isometric exercises are great for core strength, you should definately add them to your program. Also consider that there are other dynamic exercises than just crunches. As well there is other movement functions than just flexion (crunches), anti-extension/flexion (plank) and lateral anti-flexion (Side plank). Rotational (Or more preferred is anti-rotational) is also one, so is extension. For rotational strength there are as examples, exercises like Pallof Press, Landmines, and different single-handed plank variations.

To the duration.There is no one answer. You can alter two things: Time and intensity/difficulty. I personally don't like long isometric holds (45s-120s). I get bored easily and I don't think time is the important factor here. I usually do sets under 30s, with a different variations. It must be hard to meet the time goal, at least on the last set. That's important for me. Lately I've been doing one-armed planks for 3x20-30s. Another one of my favourites is Plank DB row, which I do for 6-10 reps for 3 sets both sides. Total time for set is somewhere around 15-20 seconds.

But there are other ways too. Goalie coach Maria Mountain uses very short plank intervals for example. Making them reps. Example is six sets of 10 second planks with 5-15 second rest between reps. Then repeat that 2-4 times.

I would say core/ab work should be done 1-3 times a week, only one or two exercises, for 2-4 sets of each exercise. If you have two exercises, I would do them either on seperate days or just once or twice a week.

Isometrics can build strength, but at a limited part of the muscle's ROM... the muscles weren't strong through their full ROM.

Is this a fact? I mean, can the muscle get stronger on part of its ROM and remain weak on other parts? I was under the impression that the muscle tension-length function (like the one graphed at http://www.pt.ntu.edu.tw/hmchai/BM03/BM ... Muscle.png) is a given for for each muscle.

Isometrics have about a 15 degree carry over. That doesn't make it useless though. It's useful for working through sticking points. There is also some validity to working your strongest point since the load is greatest at that point, and you wouldn't be able to work full ROM with the same load.

_________________Stu Ward_________________Let thy food be thy medicine, and thy medicine be thy food.~HippocratesStrength is the adaptation that leads to all other adaptations that you really care about - Charles Staley_________________Thanks TimD

Isometrics can build strength, but at a limited part of the muscle's ROM... the muscles weren't strong through their full ROM.

Is this a fact? I mean, can the muscle get stronger on part of its ROM and remain weak on other parts? I was under the impression that the muscle tension-length function (like the one graphed at http://www.pt.ntu.edu.tw/hmchai/BM03/BM ... Muscle.png) is a given for for each muscle.

Well, that's a good question. It's so much a part of strength training lore, that I have never really questioned it. I have always assumed that a different group of motor units came into play at different parts of the ROM, but I actually don't know this to be true.

What seems more likely to be true is for movements involving several muscles, with different ones playing a greater or lesser role at different parts of the ROM.

Isometrics are often used when a person perceives a weak part of a movement, like when your sticking point on bench is near lockout vs. just off the chest.

_________________Our greatest fear should not be of failure, but of succeeding at things in life that don't really matter.--Francis Chan

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